Methods for dyeing keratinous fibers with compositions which contain aminoindole couplers, oxidation dye precursors, and oxidizing agents at acid pHs

ABSTRACT

A method for dyeing keratin fibers, wherein a composition is applied to said fibers which contains, in a suitable dyeing medium, at least one coupler having formula (I) ##STR1## wherein R 1  is hydrogen or alkyl; R 2  and R 3  are hydrogen, alkyl, COOR&#39;, where R&#39; is alkyl or hydrogen; R 4  is hydrogen, hydroxyalkyl, alkyl, polyhydroxyalkyl or acetyl or aminoalkyl wherein the amine may be mono- or disubstituted by alkyl; Z 1  and Z 2  are hydrogen, alkyl, hydroxy, halogen, alkoxy or a salt thereof; at least one precursor of an oxidation hair dye; and at least one oxidizing agent, the pH of the composition applied to the fibers being less than 7.

This is a continuation of application Ser. No. 08/122,523, filed as PCT/FR92/00288 filed Mar. 30, 1992, now abandoned.

The present invention relates to a new process for dyeing keratinous fibers, in particular human keratinous fibers, using aminoindoles in combination with oxidation bases and an oxidizing agent in acidic medium and to the compositions used during this process and to new aminoindole compounds.

It is known to dye keratinous fibers and in particular human hair with dye compositions containing, in alkaline medium, oxidation dye precursors and in particular p-phenylenediamines or ortho or para-aminophenols, usually called "oxidation bases".

It is also known that the shades obtained with these oxidation bases can be varied by using them in combination with couplers, also known as color modifiers, chosen especially from aromatic meta-diamines, meta-aminophenols and meta-diphenols.

The applicants have surprisingly just found that the use of certain compounds of the aminoindole type in combination with oxidation bases produces colors exhibiting an excellent dyeing power when this combination is applied to hair in the presence of an oxidizing agent and at acidic pH.

The results obtained are particularly surprising when they are compared with those obtained with traditional couplers like those referred to above, where a loss in dyeing power and a lower tenacity are often found when the operation is carried out at acidic pH.

The colors thus obtained exhibit an excellent tenacity to light, washing, perspiration and inclement weather.

The subject of the present invention is therefore a process for dyeing keratinous fibers, in particular human keratinous fibers such as hair, comprising the application to these fibers of a composition containing at least one aminoindole of formula (I) as defined below, of an oxidation dye precursor also called an oxidation base and of an oxidizing agent, at acidic pH.

Another subject of the invention is a two-component dyeing agent in which one of the components comprises aminoindole and the oxidation dye precursor and the other the oxidizing agent at an acidic pH, in quantities such that the mixture exhibits an acidic pH.

A certain number of aminoindole derivatives of formula (I) as defined below, constitute new "couplers" for oxidation dyeing, when applied to keratinous fibers in combination with oxidation dye precursors.

A further subject also consists of oxidation dyeing compositions containing an oxidation dye precursor and one of these particular compounds as coupler.

Another subject of the invention is the ready-for-use composition containing the various agents employed for the dyeing of hair in acidic medium.

The invention also relates to new aminoindole compounds.

Other subjects of the invention will appear on reading the description and the examples which follow.

The process for dyeing keratinous fibers and in particular human keratinous fibers such as hair, in accordance with the invention, is essentially characterised in that there is applied to these fibers a composition containing, in a suitable medium for dyeing, at least one coupler corresponding to the formula: ##STR2## in which:

R₁ denotes hydrogen or a C₁ -C₄ alkyl group,

R₂ and R₃, independently of each other, denote a hydrogen atom, a C₁ -C₄ alkyl group or a COOR' group, R' being a C₁ -C₄ alkyl radical or a hydrogen atom,

R₄ denotes a hydrogen atom, a C₁ -C₄ alkyl radical, a C₁ -C₄ hydroxyalkyl, C₂ -C₄ polyhydroxyalkyl, acetyl or C₁ -C₆ aminoalkyl group, in which the amine may be optionally mono- or disubstituted by a C₁ -C₄ alkyl,

Z₁ and Z₂, which are identical or different, denote a hydrogen atom or a C₁ -C₄ alkyl, hydroxyl, halogen or alkoxy (C₁ -C₄) group,

and the salts of all these compounds;

at least one oxidation dye precursor,

at least one oxidizing agent, the pH of the composition applied to the fibers being lower than 7.

The preferred compounds corresponding to the formula (I) and employed in accordance with the invention are the following:

(1) 5-aminoindole,

(2) 4-aminoindole,

(3) 2-methyl-6-aminoindole,

(4) 2,3,4-trimethyl-6-aminoindole,

(5) 2,3,7-trimethyl-6-aminoindole,

(6) 2,3,5-trimethyl-6-aminoindole,

(7) 6-aminoindole,

(8) 7-aminoindole,

(9) 6-(β-hydroxyethylamino)indole,

(10) 2-methyl-5-hydroxy-6-aminoindole,

(11) 2,3-dimethyl-5-amino-6-hydroxyindole,

(12) 2,3-dimethyl-5-methoxy-6-aminoindole,

(13) 2,3-dimethyl-5-hydroxy-6-aminoindole,

(14) 2,3-dimethyl-5-ethyl-6-aminoindole,

(15) 2,3-dimethyl-5-chloro-6-aminoindole,

(16) 2,3-dimethyl-5-acetylamino-6-methoxyindole,

(17) 2,3-dimethyl-5-amino-6-methoxyindole,

(18) N-methyl-6-(β-hydroxyethyl)aminoindole,

(19) 2,3,4,5-tetramethyl-6-aminoindole.

The following compounds may also be mentioned:

(20) 6-N-methylaminoindole,

(21) N-methyl-5-aminoindole,

(22) N-methyl-6-aminoindole,

(23) N-methyl-4-aminoindole,

(24) 2,3-dimethyl-4-aminoindole,

(25) 2,3-dimethyl-7-aminoindole,

(26) 3-methyl-6-aminoindole,

(27) 2-methyl-3-ethyl-6-aminoindole,

(28) 2-methyl-3-ethyl-7-aminoindole,

(29) 4-N-methylaminoindole,

(30) 7-ethyl 4-aminoindole,

(31) 7-ethyl 6-aminoindole,

(32) 7-ethyl 6-N,β-hydroxyethylaminoindole,

(33) 4-methyl 6-aminoindole,

(34) 5-methyl 6-aminoindole,

(35) 7-methyl 4-aminoindole,

(36) 3-methyl 7-ethyl 6-aminoindole,

(37) 5,7-dimethyl 6-aminoindole,

(38) 5,7-diethyl 6-aminoindole,

(39) 2-ethoxycarbonyl 5-methyl 7-aminoindole,

(40) 2-ethoxycarbonyl 5-chloro 7-aminoindole,

(41) 2-ethoxycarbonyl 5-ethoxy 7-aminoindole,

(42) 2-ethoxycarbonyl 5-methoxy 7-aminoindole,

(43) 5-methoxy 7-(4'-dimethylamino 1'-methylbutyl)aminoindole,

(44) 5-methoxy 7-(4'-dimethylaminobutyl)aminoindole,

(45) 5-methoxy 7-(4'-diethylamino 1'-methylbutyl)aminoindole,

(46) 5-fluoro 6-aminoindole,

(47) 5-fluoro 1-sec-butyl 6-aminoindole,

(48) 5-fluoro 1-n-propyl 6-aminoindole,

(49) 1-methyl 2-methoxycarbonyl 5-methoxy 6-aminoindole,

(50) 2-methoxycarbonyl 5-methoxy 6-aminoindole,

(51) 2-ethoxycarbonyl 5-methoxy 6-aminoindole,

(52) 2-carboxy 5-methoxy 6-aminoindole,

(53) 1,2-dimethyl 5-hydroxy 6-aminoindole,

(54) 2-methoxycarbonyl 4-methoxy 6-aminoindole.

Among these compounds, 5-aminoindole, 4-aminoindole, 2-methyl-6-aminoindole, 7-aminoindole, 6-aminoindole, 6-(β-hydroxyethylamino)indole, 2-methyl-5-hydroxy-6-aminoindole and 2,3-dimethyl-5-amino-6-methoxyindole are more particularly preferred.

The salts are chosen more particularly from hydrochlorides or hydrobromides.

The oxidation dye precursors or oxidation bases are known compounds which are not dyes themselves and which form a dye by a process of oxidative condensation, either with themselves or in the presence of a coupler or modifier. These compounds generally include an aromatic nucleus carrying functional groups consisting either of two amino groups or of an amino group and a hydroxyl group, these groups being in para or ortho position relative to each other.

The oxidation dye precursors of para type which are employed in accordance with the invention are chosen from para-phenylenediamines, so-called "double" bases, para-aminophenols and para-heterocyclic precursors such as 2,5-diaminopyridine, 2-hydroxy-5-aminopyridine or 2,4,5,6-tetraaminopyrimidine.

Among para-phenylenediamines there may be mentioned the compounds corresponding to the formula (II): ##STR3## in which:

R₅, R₆ and R₇, which are identical or different, denote a hydrogen or halogen atom, an alkyl radical containing from 1 to 4 carbon atoms, an alkoxy radical containing from 1 to 4 carbon atoms, a carboxyl, sulpho or hydroxyalkyl radical containing from 1 to 4 carbon atoms,

R₈ and R₉, which are identical or different, denote a hydrogen atom or an alkyl, hydroxyalkyl, alkoxyalkyl, carbamylalkyl, mesylaminoalkyl, acetylaminoalkyl, ureidoalkyl, carbalkoxyaminoalkyl, piperidinoalkyl or morpholinoalkyl radical, these alkyl or alkoxy groups containing from 1 to 4 carbon atoms, or else R₈ and R₉, together with the nitrogen atom to which they are linked, form a piperidino or morpholino heterocyclic ring, provided that R₅ or R₇ denotes a hydrogen atom when R₈ and R₉ do not denote a hydrogen atom, and the salts of these compounds.

Among the particularly preferred compounds corresponding to the formula (II) there may be mentioned p-phenylenediamine, 2-methyl-p-phenylenediamine, methoxy-para-phenylenediamine, chloro-para-phenylenediamine, 2,6-dimethyl-para-phenylenediamine, 2,5-dimethyl-para-phenylenediamine, 2,3-dimethyl-para-phenylenediamine, 2-methyl-5-methoxy-para-phenylenediamine, 2,6-dimethyl-5-methoxy-para-phenylenediamine, N,N-dimethyl-para-phenylenediamine, 3-methyl-4-amino-N,N-diethylaniline, N,N-di(β-hydroxyethyl)-para-phenylenediamine, 3-methyl-4-amino-N,N-di(β-hydroxyethyl)aniline, 3-chloro-4-amino-N,N-di(β-hydroxyethyl)aniline, 4-amino-N,N-(ethyl,carbamylmethyl)aniline, 3-methyl-4-amino-N,N-(ethyl,carbamylmethyl)aniline, 4-amino-N,N-(ethyl,β-piperidinoethyl)aniline, 3-methyl-4-amino-N,N-(ethyl,β-piperidinoethyl)aniline, 4-amino-N,N-(ethyl,β-morpholinoethyl)aniline, 3-methyl-4-amino-N,N-(ethyl,β-morpholinoethyl)aniline, 4-amino-N,N-(ethyl,β-acetylaminoethyl)aniline, 4-amino-N-(β-methoxyethyl)aniline, 3-methyl-4-amino-N,N-(ethyl,β-acetylaminoethyl)aniline, 4-amino-N,N-(ethyl,β-mesylaminoethyl)aniline, 3-methyl-4-amino-N,N-(ethyl,β-mesylaminoethyl)aniline, 4-amino-N,N-(ethyl,β-sulphoethyl)aniline, 3-methyl-4-amino-N,N-(ethyl,β-sulphoethyl)aniline, N- (4'-amino)phenyl!morpholine, N- (4'-amino)phenyl!piperidine, 2-hydroxyethyl-para-phenylenediamine, fluoro-para-phenylenediamine, carboxy-para-phenylenediamine, sulpho-para-phenylenediamine, 2-isopropyl-para-phenylenediamine, 2-n-propyl-para-phenylenediamine, 2-hydroxymethyl-para-phenylenediamine, N,N-dimethyl-3-methyl-para-phenylenediamine, N,N-(ethyl,β-hydroxyethyl)-para-phenylenediamine, N-(dihydroxypropyl)-para-phenylenediamine, N-4'-aminophenyl-p-phenylenediamine and N-phenyl-p-phenylenediamine.

These oxidation dye precursors of para type may be introduced into the dye composition either in the form of free base or in the form of salts such as in the form of hydrochloride, hydrobromide or sulphate.

The so-called double bases are bis-phenylene-alkylenediamines, corresponding to the formula: ##STR4## in which:

R₁₂ and R₁₃, which are identical or different, denote hydroxyl or NHR₁₄ groups, where R₁₄ denotes a hydrogen atom or a lower alkyl radical,

R₁₀ and R₁₁, which are identical or different, denote either hydrogen atoms or halogen atoms or alkyl groups,

R denotes a hydrogen atom or an alkyl, hydroxyalkyl or aminoalkyl group in which the amino residue can be substituted,

Y denotes a radical taken from the group consisting of the following radicals:

--(CH₂)_(n) --, (CH₂)_(n), --O--(CH₂)_(n), --

(CH₂)_(n), --CHOH--(CH₂)_(n') ;

n being an integer between 0 and 8 and n' an integer between 0 and 4, it being possible for this base to be in the form of its addition salts with acids.

The alkyl or alkoxy radicals preferably denote a group containing 1 to 4 carbon atoms and especially methyl, ethyl, propyl, methoxy or ethoxy.

Among the compounds of formula (III), there may be mentioned N,N'-bis-(β-hydroxyethyl)-N,N'-bis(4'-aminophenyl)-1,3-diamino-2-propanol, N,N'-bis(β-hydroxyethyl)-N,N'-bis(4'-aminophenyl)ethylenediamine, N,N'-bis(4-aminophenyl)tetramethylenediamine, N,N'-bis(β-hydroxy-ethyl)-N,N'-bis(4-aminophenyl)tetramethylenediamine, N,N'-bis(4-methylaminophenyl)tetramethylenediamine and N,N'-bis(ethyl)-N,N'-bis(4'-amino-3'-methylphenyl)-ethylenediamine.

Among p-aminophenols there may be mentioned p-aminophenol, 2-methyl-4-aminophenol, 3-methyl-4-aminophenol, 2-chloro-4-aminophenol, 3-chloro-4-aminophenol, 2,6-dimethyl-4-aminophenol, 3,5-dimethyl-4-aminophenol, 2,3-dimethyl-4-aminophenol, 2-hydroxymethyl-4-aminophenol, 2-(β-hydroxyethyl)-4-aminophenol, 2-methoxy-4-aminophenol, 3-methoxy-4-aminophenol, 2,5-dimethyl-4-aminophenol, 2-methoxymethyl-4-aminophenol and 2-β-hydroxyethoxymethyl-4-aminophenol.

The oxidation dye precursors of ortho type are chosen from ortho-aminophenols such as 1-amino-2-hydroxybenzene, 6-methyl-1-hydroxy-2-aminobenzene, 4-methyl-1-amino-2-hydroxybenzene and ortho-phenylenediamines.

The oxidizing agent is preferably chosen from hydrogen peroxide, urea peroxide, alkali metal bromates and persalts such as perborates and persulphates. Hydrogen peroxide is particularly preferred.

The pH of the composition applied to the keratinous fibers, in particular hair, has a value lower than 7 and is preferably between 3 and 6.9. This pH is adjusted by the use of acidifying agents which are well known in the field of dyeing of keratinous fibers and in particular of human hair, such as of inorganic acids like hydrochloric acid or phosphoric acid or of organic ones such as carboxylic acids like tartaric or citric acid.

The compounds of formula (I) are present in the composition applied to the keratinous fibers in proportions which are preferably between 0.01 and 3.5% by weight relative to the total weight of the composition.

The compositions defined above and applied in the dyeing of keratinous fibers may also, in addition to the heterocyclic couplers of formula (I), contain other couplers which are known per se, such as meta-diphenols, meta-aminophenols, meta-phenylenediamines, meta-N-acylaminophenols, meta-ureidophenols, meta-carbalkoxyaminophenols, α-naphthol, couplers containing an active methylene group, such as diketonic compounds, pyrazolones, heterocyclic couplers or 4-hydroxyindole, 6-hydroxy-indole or 7-hydroxyindole.

Among these couplers which may be employed in addition to the couplers of formula (I) there may be mentioned 2,4-dihydroxyphenoxyethanol, 2,4-dihydroxyanisole, meta-aminophenol, resorcinol, resorcinol mono-methyl ether, 2-methylresorcinol, pyrocatechol, 2-methyl-5-N-(β-hydroxyethyl)aminophenol, 2-methyl-5-N-(β-mesylaminoethyl)aminophenol, 6-hydroxybenzomorpholine, 2,4-diaminoanisole, 2,4-diaminophenoxyethanol, 6-aminobenzomorpholine, 2-N-(β-hydroxyethyl)amino-4-amino!-phenoxyethanol, 2-amino-4-N-(β-hydroxyethyl)aminoanisole, (2,4-diamino)phenyl-β,γ-dihydroxypropyl ether, 2,4-diaminophenoxyethylamine, 1,3-dimethoxy-2,4-diaminobenzene, 2-methyl-5-aminophenol, 2,6-dimethyl-3-aminophenol, 3,4-methylenedioxyphenol, 3,4-methylenedioxyaniline, 2-chlororesorcinol and their salts.

These compositions may also contain anionic, cationic, nonionic or amphoteric surface-active agents or mixtures thereof.

Among these surface-active agents there may be mentioned alkylbenzenesulphonates, alkylnaphthalenesulphonates, sulphates, ether sulphates and fatty alcohol sulphonates, quaternary ammonium salts such as trimethylcetylammonium bromide and cetylpyridinium bromide, optionally oxyethylenated fatty acid ethanolamides, polyoxyethylenated acids, alcohols or amines, polyglycerolated alcohols or alpha-diols, polyoxyethylenated or polyglycerolated alkylphenols and polyoxyethylenated alkyl sulphates.

The dye compositions are generally aqueous but may also contain organic solvents to solubilize compounds which might not be sufficiently soluble in water. Among these solvents there may be mentioned, by way of example, C₂ -C₄ lower alkanols such as ethanol and isopropanol, glycerol, glycols or glycol ethers, such as 2-butoxyethanol, ethylene glycol, propylene glycol, diethylene glycol monoethyl ether and monomethyl ether, propylene glycol monoethyl ether and monomethyl ether and aromatic alcohols such as benzyl alcohol or phenoxyethanol, or mixtures of these solvents.

The composition applied to hair may also contain thickening agents which are chosen in particular from sodium alginate, gum arabic, cellulose derivatives such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxymethyl cellulose or carboxymethyl cellulose, optionally crosslinked acrylic acid polymers or xanthan gum. It is also possible to employ inorganic thickening agents such as bentonite.

The composition may also contain antioxidant agents chosen in particular from sodium sulphite, thioglycolic acid, sodium bisulphite, dehydroascorbic acid and hydroquinone, as well as other cosmetically acceptable adjuvants when the composition is intended to be employed for dyeing human keratinous fibers, such as penetrating agents, sequestering agents, preserving agents, buffers, perfumes, and the like.

The composition applied to hair may be presented in various forms such as liquids, creams, gels, or in any other appropriate form for producing a hair dye. It may be packaged in an aerosol bottle in the presence of a propellent agent.

A further subject of the invention is the ready-for-use composition employed in the process defined above.

According to a preferred embodiment, the process comprises a preliminary stage consisting in storing in separate form, on the one hand, the composition containing, in a suitable medium for dyeing, the coupler corresponding to the formula (I) defined above and the oxidation dye precursors in the form of a component (A) and, on the other hand, a composition containing the oxidizing agent as defined above, in the form of a component (B), and in carrying out their extemporaneous mixing before applying this mixture to the keratinous fibers, as indicated above.

The composition applied to the keratinous fibers results from mixing of 10 to 90% of the component (A) with 90 to 10% of the component (B) containing an oxidizing agent.

A further subject of the invention is an agent for dyeing keratinous fibers, in particular hair, essentially characterized in that it comprises at least two components, one of the components consisting of the component (A) defined above and the other consisting of the component (B) also defined above, the pH of the components (A) and (B) being such that after mixing in proportions of 90 to 10% in the case of the component (A) and of 10 to 90% in the case of the component (B), the resulting composition has a pH lower than 7.

In this form of embodiment the component (A) which contains at least the coupler of formula (I) and an oxidation dye precursor may have a pH of between 3 and 10.5 and may be adjusted to the chosen value by means of alkalifying agents usually employed in dyeing keratinous fibers, such as aqueous ammonia, alkali metal carbonates, alkanolamines such as mono-, di- and triethanolamines, and their derivatives or conventional acidifying agents such as inorganic acids like hydrochloric acid or phosphoric acid, or organic ones such as carboxylic acids like tartaric or citric acid.

This composition may contain the various other adjuvants referred to above, especially couplers other than aminoindole couplers corresponding to the formula (I) already mentioned above.

All of the oxidation dye precursors and the couplers are present in proportions which are preferably between 0.05 and 7% by weight relative to the total weight of the component (A). The concentration of compounds of formula (I) may vary between 0.012 and 4% by weight relative to the total weight of the component (A).

The surface-active agents are present in the component (A) in proportions of 0.1 to 55% by weight. When the mixture contains solvents in addition to water, these are present in proportions of between 0.5 and 40% by weight and in particular between 5 and 30% by weight relative to the total weight of the component (A). The thickening agents are preferably present in proportions of between 0.1 and 5% and in particular between 0.2 and 3% by weight. The antioxidant agents referred to above are preferably present in the component (A) in proportions of between 0.02 and 1.5% by weight relative to the total weight of the component (A).

The component (B) containing the oxidizing agent as defined above has a pH lower than 7. This pH may have a minimum value of 1 and is preferably between 1.5 and 3.5. This component (B) may be acidified with the same type of acidifying agents as those employed in the case of the component (A).

It may be presented in the form of more or less thickened liquid, or of milk or gel.

This two-component dyeing agent may be packaged in a multicompartment device or dyeing kit, or any other packaging system with a number of compartments one of which contains the component (A) and the second compartment contains the component (B), it being possible for these devices to be provided with a means allowing the desired mixture to be delivered onto the hair, such as the devices described in the applicants' U.S. Pat. No. 4,823,985.

A further subject of the invention is the use, as couplers, of aminoindoles corresponding to the formula (I) for the dyeing of keratinous fibers in acidic medium, in combination with oxidation dye precursors.

The dyeing process of the invention consists in applying the mixture obtained to the hair, in leaving it in place for 3 to 40 minutes and then in rinsing the hair and possibly shampooing it.

It is also possible, in accordance with the invention, to apply separately a composition containing the coupler of formula (I), the oxidation dye precursor and the oxidizing agent, so that the mixture formed in situ at the fibers has a pH lower than 7, as defined above.

The invention also relates to the use of the compounds of the following formula: ##STR5## in which:

R₁, R₂, R₃, R₄, Z₁ and Z₂ have the same meanings as indicated above, provided that when R₄ HN is in position 4, 6 or 7, Z₁ and Z₂ do not simultaneously denote a hydrogen atom, and their salts as couplers for oxidation dyeing in combination with oxidation dye precursors.

The dye compositions for keratinous fibers, in particular hair, containing, in a medium suitable for dyeing, an oxidation dye precursor and at least one of these compounds as a coupler, form another subject of the invention.

These compositions are identical with those of the component (A) of the dyeing agents according to the invention described above.

Another subject of the invention consists of the new compounds chosen from:

(30) 7-ethyl 4-aminoindole,

(31) 7-ethyl 6-aminoindole,

(33) 4-methyl 6-aminoindole,

(35) 7-methyl 4-aminoindole,

(36) 3-methyl 7-ethyl 6-aminoindole,

(10) 2-methyl 5-hydroxy 6-aminoindole,

or of formula: ##STR6## in which

R₁, R₂ and R₃ have the same meanings as those indicated above,

at least one of the groups R₂ and R₃ denotes a hydrogen atom,

R₄ denotes a C₁ -C₄ alkyl, C₁ -C₄ hydroxyalkyl or C₂ -C₄ polyhydroxyalkyl radical, --NHR₄ occupying positions 4, 6 or 7,

Z₁ and Z₂ having the same meaning as in the formula (I') defined above,

and the salts of these compounds.

The compounds (30),(31),(33) to (36) and (10) can be prepared by reduction of the corresponding nitro derivatives. Some of these nitro derivatives are known according to the paper Bergman & Sand, Tetrahedron, Vol. 46, No. 17, pages 6085 to 6112, 1990. The nitro compounds not described in this paper can be obtained by the same process, that is to say by the action of a trialkyl orthoformate on a dialkyl or trialkyl-meta-nitroaniline (one of the alkyl groups being situated in a position ortho to the amino group and para to the nitro group), in the presence of p-toluenesulphonic acid, followed by a ring closure of the product obtained.

4ethyl-6-nitroindole and 5-methyl-6-nitroindole are new.

The reduction of the nitro group is performed according to the conventional reduction processes such as, for example, by reduction with iron in acetic acid or with zinc in the presence of alcohol and of ammonium chloride, or else by catalytic hydrogenation under hydrogen pressure in the presence of a hydrogenation catalyst.

The reduction can also take place by hydrogen transfer with a transfer agent such as cyclohexene in the presence of a hydrogenation catalyst.

The hydrogenation catalyst may consist, for example, of palladium or rhodium on a support such as carbon.

In the case where Z₁ or Z₂ =Cl, the reduction is preferably done with iron in acetic acid or with zinc in the presence of alcohol and of ammonium chloride.

The compounds of formula (IA) can be prepared by the following process.

The compound (IA) can be obtained from the compound (IB) (R₄ ═H) by the methods for substitution of aromatic amines, according to the reaction scheme: ##STR7## The compound (IC) is obtained by formylation or tosylation. In a second step the compound (IC) is alkylated with alkyl halide X--R₄ to obtain the compound (ID).

The expected product (IA) is obtained by deformylation or detosylation of the compound (ID), using conventional methods.

When R₄ denotes an alkyl group, the compound (IA) can also be obtained by reduction of the compound (IE) with a metal hydride such as an alkali metal hydrobromide in the presence or absence of a Lewis acid, such as boron trifluoride etherate. ##STR8## in which formula R₁₆ denotes a C₁ -C₃ alkyl group or a hydrogen.

The compound (IE) being obtained from the compound (IB) according to the known processes for obtaining alkylcarbonylamino groups.

Among the hydroxyalkylation methods there may be mentioned the action of β-chloroalkyl chloroformate on the compound (IB), which, in a first step, makes it possible to obtain the corresponding β-chloroalkyl carbamate which, subjected to the action of a strong mineral base in a second step, makes it possible to obtain the compound (IA) in the case of which the radical R₄ is a β-hydroxyalkyl radical.

The examples which follow are intended to illustrate the present invention without, however, being limiting in nature.

EXAMPLES OF PREPARATION Example of Preparation 1 Synthesis of 4-Methyl-6-Aminoindole

1) Synthesis of 2,3-Dimethyl-5-Nitroaniline

363 g of 2,3-xylidine are run into 1.8 l of pure sulphuric acid while the temperature is kept at 40° C. To this solution, cooled to 12° C., a sulphonitric mixture (132 ml of nitric acid (d=1.52) and 180 ml of pure sulphuric acid) is added dropwise over 1 hour, the temperature not exceeding 15° C. After 15 minutes the mixture is poured onto 6 kg of ice with stirring.

The beige sulphate precipitate is filtered off, washed twice with 0.5 l of water and then three times with 0.5 l of acetone. The precipitate is slurried with 0.5 l of acetone, made alkaline with aqueous ammonia and then diluted with 1.5 l of iced water. The yellow precipitate is filtered off, washed with water and then dried. A yellow solid is obtained, which has the following characteristics:

Melting point: 110° C. Elemental analysis for C₈ H₁₀ N₂ O₂

    ______________________________________                                                   C    H           N      O                                            ______________________________________                                         Calculated  57.83  6.02        16.87                                                                               19.28                                      Found       57.91  6.03        16.78                                                                               19.20                                      ______________________________________                                    

2) Synthesis of Methyl N-(2,3-Dimethyl-5-Nitrophenyl)Formimidate

66.4 g of 2,3-dimethyl-5-nitroaniline, 0.4 l of trimethyl orthoformate and 1.6 g of para-toluenesulphonic acid are mixed and heated to reflux for 3 hours.

The mixture is poured onto 1 kg of ice, the precipitate is filtered off and is then washed twice with 0.5 l of water The precipitate is redissolved in 0.2 l of ethyl acetate and filtered hot. The solid obtained after cooling is filtered off, washed with petroleum ether and dried.

Crystallization from isopropyl ether produces white crystals which have the following characteristics:

Melting point: 108° C. Elemental analysis for C₁₀ H₁₂ N₂ O₃

    ______________________________________                                                   C    H           N      O                                            ______________________________________                                         Calculated  57.69  5.81        13.45                                                                               23.05                                      Found       57.74  5.84        13.39                                                                               23.25                                      ______________________________________                                    

3) Synthesis of 4-Methyl-6-Nitroindole

A solution of 31 g of potassium ethoxylate, 51 ml of ethyl oxalate and 0.25 l of dimethylformamide is added to a solution of methyl N-(2,3-dimethyl-5-nitrophenyl)formimidate (52 g) in 0.37 l of dimethylformamide. The temperature of the mixture is raised to 40° C. for 3 hours. The precipitate is filtered off and washed with water. The precipitate is taken up in hot isopropyl ether and then filtration is carried out.

The filtrate is evaporated and then subjected to chromatography on silica (eluent: 9/1 heptane/ethyl acetate). A yellow solid is obtained which has the following characteristics:

Melting point: 145° C. Elemental analysis for C₉ H₈ N₂ O₂

    ______________________________________                                                   C    H           N      O                                            ______________________________________                                         Calculated  61.36  4.58        15.90                                                                               18.16                                      Found       61.30  4.58        15.88                                                                               18.20                                      ______________________________________                                    

4) Synthesis of 4-Methyl-6-Aminoindole

4.3 g of nitro derivative prepared in stage 3, 20 ml of ethanol, 9 ml of cyclohexene, 3 ml of water and 2.2 g of 10% palladium on carbon are mixed and are then heated to reflux for 2 hours.

The mixture is filtered hot, the catalyst is washed with alcohol, the filtrate is evaporated under vacuum. The precipitate is taken up in isopropyl ether, treated with vegetable charcoal and then filtered on celite.

After evaporation of the filtrate a beige solid is obtained which has the following characteristics:

Melting point: 102° C. Elemental analysis for C₈ H₁₀ N₂

    ______________________________________                                                  C          H      N                                                   ______________________________________                                         Calculated 73.97        6.85   19.18                                           Found      73.84        6.99   19.06                                           ______________________________________                                    

Example of Preparation 2

Synthesis of 4-Amino-7-Methylindole

The same reduction process from point 4 of Example 1 is employed, 4-nitro-7-methylindole being employed instead of 4-methyl-6-nitroindole.

A pale yellow solid is obtained which has the following characteristics:

Melting point: 131° C. Elemental analysis for C₈ H₁₀ N₂

    ______________________________________                                                  C          H      N                                                   ______________________________________                                         Calculated 73.97        6.85   19.18                                           Found      73.95        6.94   19.11                                           ______________________________________                                    

Example of Preparation 3

Synthesis of 3-Methyl-6-Amino-7-Ethylindole

A mixture of 0.5 l of 96° ethanol, 0.5 l of glacial acetic acid and 100 g of hydrogen-reduced pure iron is heated to 90° C. 51 g of 3-methyl-6-nitro-7-ethylindole are added in portions over 15 minutes.

After 2 hours at 95° C. the ferric sludge is filtered off and the filtrate is cooled and diluted with three volumes of water. It is extracted with three times 0.5 l of ethyl acetate, the organic phases are washed, dried and evaporated. The residue is taken up in ethyl acetate, treated with vegetable charcoal, filtered and cooled.

The light beige precipitate is filtered off and washed with ethyl acetate. The solid is dissolved in 0.1 l of water and made alkaline with aqueous ammonia; an oil precipitates and then solidifies. The precipitate is filtered off and then washed to neutrality and then dried. A white solid is obtained which has the following characteristics:

Melting point: 106° C. Elemental analysis for C₁₁ H₁₄ N₂

    ______________________________________                                                  C          H      N                                                   ______________________________________                                         Calculated 75.82        8.10   16.08                                           Found      76.01        8.10   16.06                                           ______________________________________                                    

Preparation Example 4 Synthesis of 6-Nitro 7-Ethylindole

A/Preparation of 7-Ethylindoline

A solution of 145 g of 7-ethylindole in 1.45 l of dimethoxyethane was prepared. Under nitrogen atmosphere, 49.6 g of sodium borohydride then 854 g of trichloroacetic acid were added under stirring during 1 hour, the reaction temperature being maintained at 20° C. with a carbon dioxide ice bath.

After 2 hours of stirring at ambient temperature, the reaction mixture was poured under stirring in 2 l of 15% iced soda. 2 liters of water were added, then the aqueous phase was extracted with three times 0.4 l of isopropylic ether. The organic phases were washed, dried on sodium sulphate, then filtered. The filtrate was evapored for giving 150 g of oil (quantitative yield).

B/Synthesis of 6-Nitro 7-Ethylindoline

a) 147 g of 7-ethylindoline as priorly prepared were poured in 0.45 of sulphuric acid at 98% by maintaining the temperature at 10° C. 42 ml of nitric acid at 100% were mixed to 120 ml of sulphuric acid at 98%. The sulphonitric mixture was poured dropwise for 1 hour by maintaining the temperature of reaction under 5° C. After 1 hour at this temperature, 4 kg of ice were poured. The reaction mixture was neutralized with concentrated ammonia under stirring, by maintaining the temperature at 10° C. The aqueous phase was extracted with 3 times 0.4 l of ethylacetate. The organic phases were washed, dried on sodium sulphate then evaporated.

b) The oil thus obtained was dissolved in 0.3 l of chlorhydric acid 12N; a precipitate appeared and was drained. This solid was washed with ethanol and then with petroleum ether. The solid was taken up in iced water. Then the solution was brought to a basic pH with concentrated ammonia. A yellow precipitate was formed. It was drained, washed with water and dried under vacuum.

c) The solid was dissolved in 0.6 l of isopropylic ether, then 30 g of vegetable charcoal CECA L25® and 10 g of sodium sulphate were added. After filtration, the organic phase was dry evaporated. The orange oil was poured in 0.3 l of petroleum ether. The orange precipitate was drained and dried.

82 g of 6-nitro 7-ethylindole were obtained.

Melting point: 50° C. Yield: 43%

C/Preparation of 6-Amino 7-Ethylindole

38.4 g of 6-nitro 7-ethylindoline were dissolved in 120 ml of absolute ethanol to which were added 19.2 g of palladium on charcoal at 10% (moisture 50%) and then heated to reflux for 2 hours.

The catalyst was filtered, washed with 100 ml of ethanol and the organic phases were evaporated under vacuum. The dry extract was taken up in 0.4 l of isoprolylic ether by refluxing with 3 g of vegetal charcoal. The organic phases were filtered, dried on sodium sulphate then dry evaporated. The solid was crystallized in 40 ml of isopropylic ether. The white crystal were drained, dried for obtaining 25 g

Melting point: 108° C. Yield: 78%

Preparation Example 5 Synthesis of 4-Amino 7-Ethylindole

A/Synthese of 4-Nitro 7-Ethylindoline

a) 147 g of 7-ethylindoline as priorly prepared were poured in 0.45 of sulphuric acid at 98%, by maintaining the temperature at 10° C. 42 ml of nitric acid at 100% were mixed to 120 ml of sulphuric acid at 98%. The sulphonitric mixture was poured dropwise for 1 hour by maintaining the temperature of reaction under 5° C. After 1 hour at this temperature, 4 kg of ice were poured. The reaction mixture was neutralized with concentrated ammonia under stirring, by maintaining the temperature at 10° C. The aqueous phase was extracted with 3 times 0.4 l of ethylacetate. The organic phases were washed, dried on sodium sulphate, then evaporated.

b) The oil thus obtained was dissolved in 0.3 l of chlorhydric acid 12N; a precipitate appeared and was drained. This solid was washed with ethanol and then with petroleum ether. The solid was taken up in iced water. Then the solution was brought to a basic pH with concentrated ammonia. A yellow precipitate was formed. It was drained, washed with water and dried under vacuum.

c) The chlorhydric phase obtained in b) was diluted by 0.5 kg of ice, then brought to a basic pH with concentrated ammonia. The precipitate obtained was drained, washed with water, washed with 2 times 60 ml of isopropylic ether and then dried

Yield: 15% Melting Point: 68° C.

B/Preparation of 4-Amino 7-Ethylindole

4-nitro 7-ethylindoline was reduced in the same manner than 6-nitro 7-ethylindoline. 6 g of indole recrystallized from a ethylacetate/isopropylic ether (1/3) mixture were obtained.

Melting point: 123° C. Yield: 75%

Preparation Example 6 Preparation of 6-(Betachloroethylurethan)-7-Ethylindole)

8 g of betachloroformiate were poured in a suspension of 8 g of 6-amino 7-ethylindole, 5.5 g of calcium carbonate in 24 ml of dioxane at reflux for 30 minutes. The mixture was poured on ice, then acidified. The precipitate was drained, washed with water then dried. 13 g of white product were obtained

Melting point: 132° C. Yield: 98%

Preparation Example 7 Preparation of 3-(7-Ethyl-1H-Indol-6-yl)-Oxazolidin)-2-One

A mixture of 8 g of the above prepared urethan, 8 ml of 96° ethanol and 24 ml of 4N soda was refluxed for 15 minutes. The mixture was poured on ice; the precipitate was drained, washed with water, with alcohol then with petroleum ether. After drying, 6.6 g were obtained.

Melting point: 248° C. Yield: 96%

Preparation Example 8 Preparation of 7-Ethyl, 6- N, β-Hydroxyethylaminoindole

12.2 g of oxazolidone as priorly prepared at 50° C. were added to a mixture of 31.5 g of potassium hydroxide, 8 ml of water, 70 ml of ethanol. After 20 minutes at reflux, 400 g of ice were poured, the mixture was brought to a pH 5 with acetic acid. Ammonia was added until a pH 7.5-8. A white precitate was obtained, then washed with water and dried. The extraction of mother liquor gave a supplementary amount of 1.6 g. The whole content was crystallized in a ethylacetate/isopropylic ether (1/3). 8.9 g were obtained

Melting point 105° C. Yield: 82%

Examples 1 to 17

Hair dyeing is carried out by applying to permanent-waved grey hair containing 90% of white an extemporaneous mixture of the coloring composition (A) and of the oxidizing composition (B).

This mixture has the pH shown in the table of the examples which follows.

This mixture is left to act for 30 minutes and the hair is then rinsed and shampooed. After drying, the hair is dyed in the shade specified at the bottom of the tables below.

    __________________________________________________________________________     in g         1     2   3     4   5                                             __________________________________________________________________________     A) Coloring composition                                                        4-Aminoindole                    0.396                                         5-Aminoindole      0.396                                                       2-Methyl-6-aminoindole                                                                      0.438     0.438 0.438                                             2,6-Dimethyl-para-                                                                          0.627               0.657                                         phenylenediamine.2HCl                                                          para-Phenylenediamine                                                                             0.324                                                                              0.324                                                   para-Aminophenol             0.327                                             Monoethanolamine q.s. pH                                                                    8.90  9.20                                                                               9.20  9.20                                                                               8.90                                          Support      X     X   X     X   X                                             Water q.s.   100   100 100   100 100                                           B) Oxidizing composition                                                       20-volume aqueous hydrogen                                                                  100   100 100   100 100                                           peroxide                                                                       Phosphoric acid                                                                             2.50  2.50                                                                               2.50  2.50                                                                               2.5O                                          A + B w/w mixture pH                                                                        6.50  6.60                                                                               6.50  6.50                                                                               6.50                                          Shades obtained:                                                                            mahogany                                                                             brown                                                                              mahogany                                                                             intense                                                                            powerful                                                   coppery   coppery                                                                              coppery                                                                            ashen                                                                light light                                                                              duck                                                                 brown blond                                                                              blue                                          __________________________________________________________________________     in g         6     7   8     9   10                                            __________________________________________________________________________     A) Coloring composition                                                        2,3,7-Trimethyl-6-                                                                          0.522                                                             aminoindole                                                                    2-Methyl-5-hydroxy-    0.486                                                   6-aminoindole                                                                  5-Aminoindole      0.396     0.396                                             6-β-Hydroxyethylaminoindole 0.528                                         2,6-Dimethyl-para-pheny-                                                                    0.627           0.627                                             lenediamine.2HCl                                                               para-Phenylenediamine            0.324                                         para-Aminophenol   0.327                                                                              0.327                                                   Monoethanolamine q.s. pH                                                                    8.7   9.2 9.2   8.9 9.3                                           Support      X     X   X     X   X                                             Water q.s.   100   100 100   100 100                                           B) Oxidizing composition                                                       20-volume aqueous hydrogen                                                                  100   100 100   100 100                                           peroxide                                                                       Phosphoric acid                                                                             2.50  2.50                                                                               2.50  2.50                                                                               2.50                                          A + B w/w mixture pH                                                                        6     6.7 6.5   6.4 6.8                                           Shades obtained:                                                                            quite coppery                                                                            coppery                                                                              natural                                                                            mahogany                                                   deep  iride-                                                                             beige brown                                                                              coppery                                                    grey  scent         brown                                                      green                                                             __________________________________________________________________________     in g         11    12  13    14  15                                            __________________________________________________________________________     A) Coloring composition                                                        2,3-Dimethyl-5-methoxy-                                                                     0.571                                                             6-aminoindole                                                                  2,3-Dimethyl-5-chloro-                                                                            0.583                                                       6-aminoindole                                                                  2,3-Dimethyl-5-amino-  0.680                                                   6-methoxyindole.HCl                                                            2,3-Dimethyl-5-acetyl-       0.697                                             amino-6-methoxyindole                                                          2,3-Dimethyl-5-amino-            0.529                                         6-hydroxyindole                                                                2,6-Dimethyl-para-pheny-                                                                              0.627     0.627                                         lenediamine.2HCl                                                               para-Aminophenol                                                                            0.327 0.327                                                       para-Phenylenediamine        0.324                                             Monoethanolamine q.s. pH                                                                    9.1   9.1 8.8   9.2 8.9                                           Support      X     X   X     X   X                                             Water q.s.   100   100 100   100 100                                           B) Oxidizing composition                                                       20-volume aqueous hydrogen                                                                  100   100 100   100 100                                           peroxide                                                                       Phosphoric acid                                                                             2.5   2.5 2.5   2.5 2.5                                           A + B w/w mixture pH                                                                        6.7   6.3 6.4   6.6 6.4                                           Shades obtained:                                                                            pearly                                                                               pearly                                                                             iride-                                                                               matt                                                                               medium                                                     beige golden                                                                             scent dark                                                                               grey                                                             blond                                                                              chestnut                                                                             blond                                                                    light                                                                          brown                                                   __________________________________________________________________________     in g                    16      17                                             __________________________________________________________________________     A) Coloring composition                                                        7-ethyl 6-aminoindole   0,48                                                   7-ethyl 6-N, β-hydroxyethylaminoindole                                                            --      0.61                                           2,6-dimethylparaphenylenediamine dichlorhydrate                                                        0.63    0.63                                           Monoethanolamine qs pH  9.8     9.8                                            Support                 X       X                                              Water q.s.              100     100                                            B) Oxidizing composition                                                       20-volume aqueous hydrogen peroxide                                                                    100     100                                            Phosphoric acid         2.5     2.5                                            A + B w/w mixture pH    6.7     6.6                                            Shades obtained:        iridescent                                                                             iridescent                                                             chesnut chestnut                                                               red     red                                                                    mahogany                                                                               mahogany                                       __________________________________________________________________________

    ______________________________________                                         Oleyl alcohol polyglycerolated with                                                                      4.0    g                                             2 moles of glycerol                                                            Oleyl alcohol polyglycerolated with                                                                      5.69   g AS                                          4 moles of glycerol containing 78%                                             of AS                                                                          Oleic acid                3.0    g                                             Oleylamine containing 2 moles of                                                                         7.0    g                                             ethylene oxide, sold by Akzo under the                                         name Ethomeen O 12 ®                                                       Diethylaminopropyl laurylaminosuccina-                                                                   3.0    g AS                                          mate, sodium salt containing 55% of AS                                         Oleyl alcohol             5.0    g                                             Oleyl diethanolamide      12.0   g                                             Propylene glycol          3.5    g                                             Ethyl alcohol             7.0    g                                             Diproylene glycol         0.5    g                                             Propylene glycol monomethyl ether                                                                        9.0    g                                             Sodium metabisulphite in aqueous                                               solution containing 35% of AS                                                                            0.45   g AS                                          Ammonium acetate          0.8    g                                             Antioxidant, sequestrant q.s.                                                  Perfume, stabilizers q.s.                                                      ______________________________________                                     

We claim:
 1. A method for dyeing keratinous fibers comprisingapplying to said keratinous fibers a composition containing, in a medium for dyeing said fibers, (a) coupler having the formula ##STR9## wherein R₁ represents hydrogen or C₁ -C₄ alkyl, R₂ and R₃, each independently, represent hydrogen, C₁ -C₄ alkyl or COOR' wherein R' represents C₁ -C₄ alkyl or hydrogen, R₄ represents hydrogen, C₁ -C₄ alkyl, C₁ -C₄ hydroxyalkyl, C₂ -C₄ polyhydroxyalkyl, acetyl or C₁ -C₆ aminoalkyl wherein the amine moiety is unsubstituted or mono- or disubstituted by C₁ -C₄ alkyl, Z₁ and Z₂, each independently, represent hydrogen, C₁ -C₄ alkyl, hydroxyl, halogen or alkoxy (C₁ -C₄), and the salts thereof;(b) an oxidation dye precursor; and (c) an oxidizing agent selected from the group consisting of hydrogen peroxide, urea peroxide, alkali metal bromates and persalts, said oxidizing agent being present in an amount effective to develop coloration of said coupler and said oxidation dye precursor, the pH of said composition being less than
 7. 2. The method of claim 1 wherein said coupler of formula (I) is selected from the group consisting of5-aminoindole, 4-aminoindole, 2-methyl-6-aminoindole, 2,3,4-trimethyl-6-aminoindole, 2,3,7-trimethyl-6-aminoindole, 2,3,5-trimethyl-6-aminoindole, 6-aminoindole, 7-aminoindole, 6-(β-hydroxyethylamino)indole, 2-methyl-5-hydroxy-6-aminoindole,
 2. 3-dimethyl-5-amino-6-hydroxyindole,2,3-dimethyl-5-methoxy-6-aminoindole, 2,3-dimethyl-5-hydroxy-6-aminoindole, 2,3-dimethyl-5-ethyl-6-aminoindole, 2,3-dimethyl-5-chloro-6-aminoindole, 2,3-dimethyl-5-acetylamino-6-methoxyindole, 2,3-dimethyl-5-amino-6-methoxyindole, N-methyl-6-(β-hydroxyethyl)aminoindole, 2,3,4,5-tetramethyl-6-aminoindole, 6-N-methylaminoindole, N-methyl-5-aminoindole, N-methyl-6-aminoindole, N-methyl-4-aminoindole, 2,3-dimethyl-4-aminoindole, 2,3-dimethyl-7-aminoindole, 3-methyl-6-aminoindole, 2 methyl-3-ethyl-6-aminoindole, 2-methyl-3-ethyl-7-aminoindole, 4-N-methylaminoindole, 7-ethyl-4-aminoindole, 7-ethyl-6-aminoindole, 7-ethyl-6-N,β-hydroxyethylaminoindole, 4-methyl-6-aminoindole, 5-methyl-6-aminoindole, 7-methyl-4-aminoindole, 3-methyl-7-ethyl-6-aminoindole, 5,7-dimethyl-6-aminoindole, 5,7-diethyl-6-aminoindole, 2-ethoxycarbonyl-5-methyl-7-aminoindole, 2-ethoxycarbonyl-5-chloro-7-aminoindole, 2-ethoxycarbonyl-5-ethoxy-7-aminoindole, 2-ethoxycarbonyl-5-methoxy-7-aminoindole, 5-methoxy-7-(4'-dimethylamino-1'-methylbutyl) aminoindole, 5-methoxy-7-(4'-dimethylaminobutyl) aminoindole, 5-methoxy-7-(4'-diethylamino-1'-methylbutyl) aminoindole, 5-fluoro-6-aminoindole, 5-fluoro-1-sec-butyl-6-aminoindole, 5-fluoro-1-n-propyl-6-aminoindole, 1-methyl-2-methoxycarbonyl-5-methoxy-6-aminoindole, 2-methoxycarbonyl-5-methoxy-6-aminoindole, 2-ethoxycarbonyl-5-methoxy-6-aminoindole, 2-carboxy-5-methoxy-6-aminoindole, 1,2-dimethyl-5-hydroxy-6-aminoindole, 2-methoxycarbonyl-4-methoxy-6-aminoindole, and a salt thereof.
 3. The method of claim 1 wherein said oxidation dye precursor is selected from the group consisting of a para-phenylenediamine, a para-aminophenol, a para-heterocyclic precursor and a double base.
 4. The method of claim 3 wherein said para-phenylenediamine has the formula ##STR10## wherein R₅, R₆ and R₇, each independently, represent hydrogen, halogen, C₁ -C₄ alkyl, C₁ -C₄ alkoxy, carboxyl, sulpho containing 1-4 carbon atoms or hydroxyalkyl containing 1-4 carbon atoms,R₈ and R₉, each independently, represent hydrogen, alkyl, hydroxyalkyl, alkoxyalkyl, carbamylalkyl, mesylaminoalkyl, acetylaminoalkyl, ureidoalkyl, carbalkoxyaminoalkyl, piperidinoalkyl or morpholinoalkyl, said alkyl or alkoxy groups containing 1-4 carbon atoms, or R₈ and R₉ together with the nitrogen atom to which they are attached form a piperidino or morpholino heterocyclic ring, with the proviso that R₅ and R₇ represent hydrogen when R₈ and R₉ do not represent hydrogen, and a salt thereof.
 5. The method of claim 4 wherein said para-phenylenediamine is selected from the group consisting ofp-phenylenediamine, 2-methyl-p-phenylenediamine, methoxy-para-phenylenediamine, chloro-para-phenylenediamine, 2,6-dimethyl-para-phenylenediamine, 2,5-dimethyl-para-phenylenediamine, 2,3-dimethyl-para-phenylenediamine, 2-methyl-5-methoxy-para-phenylenediamine, 2,6-dimethyl-5-methoxy-para-phenyldiamine, N,N-dimethyl-para-phenyldiamine, 3-methyl-4-amino-N,N,-diethylaniline, N,N-di(β-hydroxyethyl)-para-phenylenediamine, 3-methyl-4-amino-N,N-di(β-hydroxyethyl)aniline, 3-chloro-4-amino-N,N-di(β-hydroxyethyl)aniline, 4-amino-N,N-(ethyl,carbamylmethyl)aniline, 3-methyl-4-amino-N,N-(ethyl,carbamylmethyl)aniline 4-amino-N,N-(ethyl,β-piperidinoethyl)aniline, 3-methyl-4-amino-N,N-(ethyl,β-piperidinoethyl) aniline, 4-amino-N,N-(ethyl,β-morpholinoethyl)aniline, 3-methyl-4-amino-N,N-(ethyl,β-morpholinoethyl)anilene, 4-amino-N,N-(ethyl,β-acetylaminoethyl)aniline, 4-amino-N-(β-methoxyethyl)aniline, 3-methyl-4-amino-N,N-(ethyl,β-acetylaminoethyl)aniline, 4-amino-N,N-(ethyl,β-mesylaminoethyl)aniline, 3-methyl-4-amino-N,N-(ethyl,β-mesylaminoethyl)aniline, 4-amino-N,N-(ethyl,β-sulphoethyl)aniline, 3-methyl-4-amino-N,N-(ethyl,β-sulphoethyl)aniline, N- (4'-amino)phenyl! morpholine, N- (4'-amino)phenyl! piperidine, 2-hydroxyethyl-para-phenylenediamine, fluoro-para-phenylenediamine, carboxy-para-phenylenediamine, sulpho-para-phenylenediamine, 2-isopropyl-para-phenylenediamine, 2-N-propyl-para-phenylenediamine, 2-hydroxymethyl-para-phenylenediamine, N,N-dimethyl-3-methyl-para-phenylenediamine, N,N-(ethyl,β-hydroxyethyl)-para-phenylenediamine, N-(dihydroxypropyl)-para-phenylenediamine, N-4'-aminophenyl-p-phenylenediamine and N-phenyl-p-phenylenediamine, said para-phenylenediamine being in the form of a free base or a salt.
 6. The method of claim 3 wherein said para-aminophenol is selected from the group consisting ofp-aminophenol, 2-methyl-4-aminophenol, 3-methyl-4-aminophenol, 2-chloro-4-aminophenol, 3-chloro-4-aminophenol, 2,6-dimethyl-4-aminophenol, 3,5-dimethyl-4-aminophenol, 2,3-dimethyl-4-aminophenol, 2-hydroxymethyl-4-aminophenol, 2-(β-hydroxyethyl)-4-aminophenol, 2-methoxy-4-aminophenol, 3-methoxy-4-aminophenol, 2,5-dimethyl-4-aminophenol, 2-methoxymethyl-4-aminophenol and 2-β-hydroxyethoxymethyl-4-aminophenol.
 7. The method of claim 3 wherein said double base is a bis-phenylalkylenediamine having the formula ##STR11## wherein R₁₂ and R₁₃, each independently, represent hydroxyl or NHR₁₄,R₁₄ represents hydrogen or lower alkyl, R₁₀ and R₁₁, each independently, represents hydrogen halogen or alkyl, R represents hydrogen, alkyl, hydroxy alkyl or aminoalkyl wherein the amino moiety is unsubstituted or substituted, Y represents a member selected from the group consisting of --(CH₂)_(n) --, (CH₂)_(n') --O--(CH₂)_(n'), (CH₂)_(n') --CHOH--(CH₂)_(n'),wherein n is an integer between 0 and 8 and n' is an integer between 0 and 4, and an acid addition salt thereof.
 8. The method of claim 7 wherein said double base is selected from the group consisting ofN,N'-bis-(β-hydroxyethyl)-N,N'-bis(4'-aminophenyl)-1,3-diamino-2-propanol, N,N'-bis(β-hydroxyethyl)-N,N'-bis(4'-aminophenyl) ethylenediamine, N,N'-bis(4-aminophenyl)tetramethylenediamine, N,N'-bis(β-hydroxyethyl)-N,N'-bis(4-aminophenyl)tetramethylenediamine, N,N'-bis(4-methylaminophenyl)tetramethylene diamine and N,N'-bis(ethyl)-N,N'-bis(4'-amino-3'-methylphenyl)ethylenediamine.
 9. The method of claim 1 wherein said oxidation dye precursor is selected from the group consisting of an ortho-aminophenol and an ortho-phenylenediamine.
 10. The method of claim 1 wherein the pH of said composition applied to said keratinous fibers ranges from 3 to 6.9.
 11. The method of claim 1 wherein said composition contains an additional coupler selected from a meta-diphenol, a meta-aminophenol, a meta-phenylenediamine, a meta-N-acylaminophenol, a meta-ureidophenol, a meta-carbalkoxyaminophenol, α-naphthol, a diketonic compound, a pyrazolone, a heterocyclic coupler, 4-hydroxyindole, 6-hydroxyindole or 7-hydroxyindole.
 12. The method of claim 11 wherein said additional coupler is selected from the group consisting of2,4-dihydroxyphenoxyethanol, 2,4-dihydroxyanisole, meta-aminophenol, resorcinol, resorcinol monomethyl ether, 2-methylresorcinol, pyrocatechol, 2-methyl-5-N-(β-hydroxyethyl)aminophenol, 2-methyl-5-N-(β-mesylaminoethyl)aminophenol, 6-hydroxybenzomorpholine, 2,4-diaminoanisole, 2,4-diaminophenoxyethanol, 6-aminobenzomorpholine, 2-N-(β-hydroxyethyl)amino-4-amino!phenoxyethanol, 2-amino-4-N-(β-hydroxyethyl)aminoanisole, (2,4-diamino)phenyl-β,γ-dihydroxypropyl ether, 2,4-diaminophenoxyethylamine, 1,3-dimethoxy-2,4-diaminobenzene, 2-methyl-5-aminophenol, 2,6-dimethyl-3-aminophenol, 3,4-methylenedioxyphenol, 3,4-methylenedioxyaniline, 2-chlororesorcinol, and a salt thereof.
 13. The method of claim 1 wherein said composition contains an anionic, cationic, nonionic or amphoteric surface-active agent or a mixture thereof; a thickening agent or an antioxidant agent.
 14. The method of claim 1 wherein said medium suitable for dyeing said fibers is water or a mixture of water and a solvent selected from a C₂ -C₄ lower alkanol, glycerol, a glycol, a glycol ether, an aromatic alcohol, or a mixture thereof.
 15. An agent for dyeing keratinous fibers comprising(a) a component (A) comprising, in a dyeing medium, an aminoindole coupler of formula (I) ##STR12## wherein R₁ represents hydrogen or C₁ -C₄ alkyl, R₂ and R₃, each independently, represent hydrogen, C₁ -C₄ alkyl or COOR' wherein R' represents C₁ -C₄ alkyl or hydrogen, R₄ represents hydrogen, C₁ -C₄ alkyl, C₁ -C₄ hydroxyalkyl, C₂ -C₄ polyhydroxyalkyl, acetyl or C₂ -C₆ aminoalkyl wherein the amine moiety is unsubstituted or mono- or disubstituted by C₁ -C₄ alkyl, Z₁ and Z₂, each independently, represent hydrogen, C₁ -C₄ alkyl, hydroxyl, halogen or alkoxy (C₁ -C₄), and the salts thereof,and an oxidation dye precursor and (b) a component (B) comprising, in a dyeing medium, an oxidizing agent selected from the group consisting of hydrogen peroxide, urea peroxide, alkali metal bromates and persalts, the pH of said components (A) and (B) being such that after mixing in proportions of 90 to 10% of component (A) with 10 to 90% of component (B), the resulting composition has a pH lower than
 7. 16. The agent of claim 15 wherein component (A) has pH ranging from 3 to 10.5.
 17. The agent of claim 15 wherein said component (A) contains said oxidation dye precursor and aminoindole coupler in an amount ranging from 0.5 to 7 percent by weight relative to the total weight of said component (A).
 18. The agent of claim 15 wherein said aminoindole coupler of formula (I) is present in an amount ranging from 0.012 to 4 percent by weight relative to the total weight of said component (A).
 19. The agent of claim 15 wherein said component (A) also contains at least one ofa surface-active agent in an amount ranging from 0.1 to 55 percent by weight, a solvent in an amount ranging from 0.5 to 40 percent by weight, a thickening agent in an amount ranging from 0.1 to 5 percent by weight, and an antioxidant agent in an amount ranging from 0.02 to 1.5 percent by weight.
 20. The agent of claim 15 wherein said component (B) has a pH lower than 7 and a minimum value of
 1. 21. A process for dyeing keratinous fibers comprising a first stage comprising storing said dyeing agent of claim 15 and mixing said components (A) and (B) before application to said keratinous fibers in amounts of 10 to 90 percent of said component (A) and 90 to 10 percent of said component (B) to produce a resulting composition having a pH lower than 7, and applying said resulting composition to said keratinous fiber immediately after preparation of said resulting composition.
 22. A multicompartment device or dyeing kit comprising at least two compartments, one said compartment containing said component (A) defined in claim 15 and the other compartment containing said component (B) defined in claim
 15. 23. The multicompartment device or dyeing kit of claim 22 having means to permit the mixture of said component (A) and component (B) to be delivered onto hair.
 24. The method of claim 1 for dyeing hair comprising applying said composition to hair and permitting said composition to remain in contact with said hair for a period of time ranging from 3 to 40 minutes, rinsing said hair, optionally shampooing said hair prior to a second hair rinsing, and drying said hair.
 25. A composition for dyeing keratinous fibers comprising, in a medium for dyeing said fibers, a dye effective amount of(a) a coupler having the formula ##STR13## wherein R₁ represents hydrogen or C₁ -C₄ alkyl, R₂ and R₃, each independently, represent hydrogen, C₁ -C₄ alkyl or COOR' wherein R' represents C₁ -C₄ alkyl or hydrogen, R₄ represents hydrogen, C₁ -C₄ alkyl, C₁ -C₄ hydroxyalkyl, C₂ -C₄ polyhydroxyalkyl, acetyl or C₁ -C₆ aminoalkyl wherein the amine moiety is unsubstituted or mono- or disubstituted by C₁ -C₄ alkyl, Z₁ and Z₂, each independently, represent hydrogen, C₁ -C₄ alkyl, hydroxyl, halogen or alkoxy (C₁ -C₄), and the salts thereof;(b) an oxidation dye precursor; and (c) an oxidizing agent selected from the group consisting of hydrogen peroxide, urea peroxide, alkali metal bromates and persalts, said oxidizing agent being present in an amount effective to develop coloration of said coupler and said oxidation dye precursor, the pH of said composition being less than
 7. 26. The composition of claim 25, wherein said coupler of formula (I) is present in an amount ranging from 0.01 to 3.5 weight percent relative to the total weight of said composition.
 27. A composition for dyeing keratinous fibers comprising in a medium for dyeing said keratinous fibers a component (A) comprising an oxidation dye precursor and a coupler having the formula ##STR14## wherein R₁ represents hydrogen or C₁ -C₄ alkyl,R₂ and R₃, each independently, represent hydrogen, C₁ -C₄ alkyl or COOR' wherein R is C₁ -C₄ alkyl, R₄ represents hydrogen, C₁ -C₄ alkyl, C₁ -C₄ hydroxyalkyl, C₂ -C₄ polyhydroxyalkyl, acetyl or C₁ -C₆ aminoalkyl wherein the amine moiety optionally may be mono- or disubstituted by C₁ -C₄ alkyl, Z₁ and Z₂, each independently, represent hydrogen, C₁ -C₄ alkyl, hydroxyl, halogen or C₁ -C₄ alkoxy, with the proviso that when NHR₄ is in position 4, 6 or 7, Z₁ and Z₂ are not hydrogen simultaneously, and the salts thereof, and a component (B) comprising an oxidizing agent selected from the group consisting of hydrogen peroxide, urea peroxide, alkali metal bromates and persalts, the pH of said components (A) and (B) being such that after mixing in proportions of 90 to 10% of component (A) with 10 to 90% of component (B), the resulting composition has a pH lower than
 7. 